If the copper or brass shapes are bent, straighten them with a steel block and nylon or rawhide mallet. (Solder doesn't fill gaps.)
File/sand/polish to any rough edges or deep scratches.
Snip 5-10 tiny (1-2mm long) pieces of solder into a small bowl.
Use a small paintbrush to coat the back of the brass "ninja star", and the front of the copper disk with flux. (You may need to mix the flux to a more paste-like consistency.)
Place the disk on a magnesia soldering block.
Place tiny pieces of solder on the disk, where the brass star will be soldered. (If possible, stick them to the flux on the back of the brass star instead.)
Carefully place the brass star onto the disk and use tweezers and a soldering pick to make sure everything is perfectly in place, and the solder is hiding safely underneath.
Gently apply heat with the torch, starting on the block itself, circling around the outside of the copper, and then slowly bringing heat to the center. Your goal is to heat the piece to the soldering temperature without over-heating the brass. If you overheat the brass, or hold it at high heat for too long, the copper in it migrates to the surface and makes it look like you just soldered a piece of copper to copper.
Quench in cool water.
Pickle (follow instructions on package) and/or scrub briefly with a green scrubbie and tumble polish for a few hours. How long you need to pickle or polish will vary depending on if or how much copper you accidentally brought to the surface when soldering the brass.
Texture as Desired:
For a glittery sanded effect, use a Micro Engraver (or flex shaft and grinding point) on the center star. Go back and forth across the star at a consistent angle, and be careful not to go past the edges. Bonus ... this can also help you get rid of that pesky excess copper.
Use the ball end of a chasing or ballpein hammer to texture the copper disk. Be careful not to hit the center star.
Apply a layer of Renaissance® wax or other sealant. Let dry.
Add Beads and Stitch Soldered Disk to Leather Bracelet:
Make a sticky-paper bead template, to help punch holes in the desired locations on the copper disk: Set a 2-hole Czech lentil bead on top of a scrap of sticker paper or the front of the sticky portion of a Post-it®. Trace around the bead. Very precisely put dots on the paper to match the holes in the bead.
Cut out paper circle, think about the angles you want your "stitches" to go across the bead, and place the sticker on the copper disk. Punch 1/16" holes. Move template to other side of disk and repeat.
Set the copper disk on the leather bracelet, and if the punch you used for the disk reaches far enough, use the disk as your template and punch the leather holes for one bead directly though the holes in the copper disk. If the punch doesn't reach far enough, use an awl, drill, leather punch or other tools to punch leather. Or you can change the design so the bead's holes are closer to the edges of the bracelet.
Optional: Use bracelet-bending pliers to slightly curve disk to the same curvature the leather bracelet takes on when worn.
Cut one 4" piece of 26-gauge bare copper wire. Gently fold the middle so the wire is a U shape. Place a bead on this U, then run the wires down through the holes in the copper and through the bracelet. Gently pull tight, avoiding kinks. Run one end of the wire back up through one hole, pull tight, then back down through the other side. Gently pull tight. Pull each wire past the other wire's hole (under the bracelet) so you have 3 lines of wire, and then carefully take one end and stitch/coil it around the resulting bottom wires approx. 3 times. Trim. Repeat with other end of wire.
Gently adjust disk on bracelet, punch remaining holes and repeat stitching process. Trim excess wire and try to tuck any stray ends between the wire and leather, so they aren't scratchy.
Inspiration for Avocado Dorado - "Pablo Picasso" by The Modern Lovers : The girls would turn the colour of a juicy avocado When he would drive down their street in his El Dorado Pablo Picasso ... (NSFW)